Background: The aim of this clinical study was to evaluate the association of locally delivered doxycycline 10% with scaling and root planing in the periodontal treatment of smokers during a 2-year period.

Methods: Forty-eight chronic periodontitis patients, presenting a minimum of four pockets (≥5 mm) that bled on probing on anterior teeth were included. Patients were randomly assigned to receive one of the following treatments: scaling and root planing (SRP) and scaling and root planing followed by local application of doxycycline (SRP-D). Assigned treatments were performed at baseline and at 12 months. Clinical parameters, including probing depth (PD) and relative attachment level (RAL), were recorded at baseline; 45 days; 3, 6, and 12 months (retreatment); 45 days following retreatment; and at 15, 18, and 24 months.

Results: In initially deep pockets (≥7 mm), SRP-D showed greater PD reduction than SRP at 6 and 18 months (mean difference between groups of 1.18 and 1.73 mm, respectively; P <0.05) and greater RAL gain in all periods after 3 months (mean difference between groups of 1.16, 1.99, and 1.78 mm, at 6, 18, and 24 months, respectively; P <0.05). Also, the proportion of sites showing ≥2 mm PD reduction was greater for SRP-D at 6 months (81.2% × 50.8%; P <0.001) and at 24 months (65.5% × 46.5%; P = 0.01). As for RAL gain, this proportion was 34.4% and 18.1% for SRP-D and SRP at 24 months, respectively (P = 0.008).

Conclusion: The use of locally delivered doxycycline may constitute an important adjunct for the active and supportive treatments of severe periodontal disease in smokers.